Faulty Dimitrov lets Murray off the hook in Miami

Andy Murray was thankful for a serving capitulation from Grigor Dimitrov as he saved two set points and fought back from 5-2 down in the first to reach the fourth round of the Sony Open on Monday.

Murray was facing a man to whom he had not lost in two previous encounters, although Dimitrov's style of play has earned him the tag of "baby Federer" - such is the 21-year-old's potential. As he served for the first set it appeared Dimitrov was set for a major career scalp, but he suddenly lost all composure en route to a 7-6(3) 6-3 loss.

Dimitrov's first opportunity came on Murray's serve when, at 2-5 and 15-40, the Brit managed to claw his way to 5-3. However, Dimitrov still had the chance to close out the set on his own delivery, but inexplicably coughed up three double-faults to allow Murray back on level terms.

It was a real choker for the Bulgarian, who had dictated to the world No. 3 for the first eight games. Murray was taken to deuce in his first service game and then broken in his second. He immediately hit back to level the match but Dimitrov broke again for 4-2.

Then came the drama when, after an easy service hold for 5-2 Dimitrov allowed Murray off the hook when holding set points on his rival's delivery. That failure appeared to jolt the confidence of the 21-year-old, who twice offered Murray break point with double-faults in his next service game, throwing in another to gift Murray entry back into the contest.

A tiebreaker was eventually needed to settle what had been an unpredictable set, and for the first time in the match Murray looked assured as he dominated it 7-3.

Dimitrov is still trying to find consistency in his embryonic career, without an ATP Tour title to date and boasting a mediocre 10-6 record in 2013. His Miami meltdown against Murray provided partial evidence for why he is not yet lifting silverware, and the Brit took full advantage.

An immediate break in the second handed Murray control as he stormed into a 3-0 lead, and he rode that advantage to the finish line in a shade under two hours.

Murray will now meet Andreas Seppi for a place in the quarter-finals after Seppi saw off Thomaz Bellucci 7-5 4-6 6-2. The Italian is seeded 16th in the men's draw this week.

Plenty of other big names will join Murray in the last-16 after world No. 8 Jo-Wilfried Tsonga overcame Jarkko Nieminen 6-3 6-3. Tomas Berdych, the world No. 6, was made to work significantly harder in his 2-6 7-6(6) 6-4 win over Alejandro Falla.

Elsewhere, there were 6-3 6-4 wins for eighth seed Richard Gasquet and tenth seed Nicolas Almagro over Mikhail Youzhny and David Goffin respectively, and Sam Querrey also advanced.